Fixation of dyes on colored paper



Patented Sept. 12, 1933 UNITED STATES 1,92%,tl4 Y PATEN FIXATION F DYES0N COLORED PAPER No Drawing.

Claims.

This invention relates to a method for'the fixation of the dyes oncolored paper and more particularly to a method for rendering the dyespresent on surface colored paper non bleeding 5. or relatively fast tothe action of water and relates also to the resulting product.

In the art, it is often the practice to color paper after the sheet asbeen formedrather than by adding the dye tufi to the pulp when in the \1J tion is. carried to the sheet upon the surface of v a roll is oftenaccomplished by placing dye boxes upon the calender stack in contactwith the calender rolls. Coloring and calendering are thus accomplishedin one operation and the process is known as calender dyeing.

Acid dyes are usually preferred for surface coloring because theypossess great tinctorial value and brightness 'of shade withsatisfactory iastness to light. On the other hand, since the acid dyeshave 'very little afinity for cellulose, they are held to the surface ofthe dry paper after it has been colored by any of the above processesmerely by mechanical forces. Although 1 direct dyes have much more realamnity for "cellulose than acid dyes, paper which has been surfacecolored with direct dyes also bleeds much more than paper. which hasbeen dyed in the beater because much of the direct dye likewise Whenpaper so colored comes into contact with water, a partial resolution ofthe dye occurs. This is objectional for two reasons: First, theappearance of the paper is harmed by the resulting spots and streaks;Second, any nearby object coming into contact with the paper in thepresence of water is badly This invention as anobject the rendering ofthe dyestufif on surface colored paper relatively insoluble in water.This object be accomplished by the following invention. Paper, surfacecolored with'acid or direct dyes either in the wet or state, is mm ithin. guanidine in excess of the theoretical ount required to precipitatethe dye. The complex formed by the w n' dine is held to the surfacemerely by mechanical forces.

, of a weak acid exhibits less tendering action :1

Application July 24, 1931 Serial No. 553,008 1 with the dye isrelatively insoluble in. water. However, the presence of excess diarylguanidine causes more complete precipitation which results in lesstendency for the dye to bleed.

My invention is generally applicable in connec- W tion with all dyesthat-are characterized by the presence of acid groups, such as, forexample, the sulfonic acid or carboxylgroups, indeed to all dyes whichgive rise to colored anions when dissolved in aqueous solution. It isalso in. many cases of advantage to use a penetrating agent, such as,for example, methyl or ethyl alcohol or a higher alcohol.

The process may be applied to calender dyeing by placing a box uponthecalender stack in such a position that the paper, after being coatedwith the dye solution contained in one box, is coated with diarylg'uanidine solution contained in a second box. For example, the processmay be satisfactorily applied, in this manner to Kraft. 7 linedcontainer board The dye solution con-- taining 9 pounds 10 ounces ofmetanh yellow (C. I. No. 138)- in 216 gallons of water is applied irom'the top box on the calender stack. An approximately 10% solutionofdiphenyl guani dine hydrochloride is prepared by pasting" 6' pounds 10ounces of diphenyl guanidine with 3 pounds 3 ounces of concentrated(38%) hydrochloric acid and'diluting to eight gallons. This solution isapplied continuously to the board from 35 a lower box on the calenderstack after the board has been colored from the box on an upper roll.

When-surface dyed paper is dipped or calendered in a solution ofdiphenyl guanidine hydro:-

chloride which contains enough free hydrochloric acid to be acid toCongo red, e. g. an excess of I a% over theaniount necessary to form thehydrochloride, and is then heated in an oven, at me C. for an hour, thetensile strength of the paper is decreased more than 25%. The tearingstrength is probably decreased still more. It is therefore desirable toprepare the solution of the diaryl guanidine for after treatment in sucha way that it does not contain an excess of strong acid. j 1% Weakacids, such as acetic acid and hydrofluoric acid, the advantage forforming a soluble salt 'of th diaryl guanidine so that an exces a@mparable excess of a strong, or highly io'. 1 acid. The character ofthe acid'employed to dissolve-the new dine has nothing to do with theproperty of the yl guanidine in rendering the dye inmluble so longtheacid in question b the free base into solution spi ficiently that itcan react with the dye. Experiments show that dyed paper is not tenderedbe- .cause of after treatment with a salt of diaryl guanidine when thesolution employed for after '-treatment is neutral in reaction, evenwhen the in the dry state by evaporation of the aqueous .solution.,Th'edry salt is not very hygroscopic and yet dissolves readily; it isconvenient to handle and to ship and possesses the advantage ofcontaining no excess acid even when the solution from which it ismade-by evaporation is slightly acid., s

The dyestufi may be any acid or. direct color or any combination of dyesfrom these twoclasses. Direct dyes-form non-bleeding complexes upontreatment with solutions containing approximate-' ly one-eighthmolecular weight of diaryl guanidine per liter of solution. Acid dyesrequire higher concentrations of the diaryl guanidine, yarying fromone-eighth molecular weight per liter to, one molecular weight per.liter. It will. be understood that the amount of diaryl guanidinerequired tobring about a fairly complete precipi-v tation of the dye,will vary with each individual case and is dependentupon'the solubilityof the complex formed, upon the number of acidic groups im'the dye, uponthe depth of shade of the dyeing, 'upon the absorbency of the paper,

and upon the method by which the treatment is carried out. For thesereasons the diaryl guanidine solution may .vary in concentration from'relatively soluble, such as guinoline yellow Conc.

plied by the calendering method satisfactorily (C. \I. No; 801) andtartrazine O (C. I.--No. 640) when fixed by the calendering process.Acnefourth molar solution of diaryl guanidine apfixes any of thefollowing direct dyes which have Q been applied to the surface, ofpaper:

Du Pont brilliant paper yellow Conc. (.C. I. No. 364), Du Pont stilbeneyellow G Gone. (0. I.

' No. 622), pontamine fast scarlet 4138 (C. I. No.

326), pontamlne fastred BBL (C. I. No. 278), pontamine sky blue 63X (C.I. No. 518), p0ntamine green GK ((3. I. No.r594), pontamine black E (C.I. No. 581) et cetera. 1

Acid dyes such as pontacyl green NV Conc.

' (0. I. 'No. 735), pontacyl fast blue R (c. I. No.

208), pontacyl'fast violet 103 (C. I. No. 696),

- Du Pont crocein scarlet N Extra (0.1. No. 252) and Du Pontmetanil'yellow Conc. (C. I. No. 138) may be satisfactorily renderednon-bleed-. ing by coating sheets, surface coloredwith these- -dyes inmoderately heavy'shades, with ahalf molar solution of diaryl guanidineby the calen-. dering process. some acid dyes, such as pontacyl blueblack SX- (C. I. No. 246) Du Pont naphthol green B (0.1. No. 5) andporitacyl violet 43L -(C. I. No. 693), require a diarylguanidine'solution of lower concentration for fixation than the I 252),diluted to one gallon. Paper surface dyed with the above solution isrendered non-bleeding by passage between rolls one of which carries-aproper concentrations paper.

film of one-fourth'molar diphenyl guanidine hydrochloride solution.

Any diaryl-guanidine may be employed as the I fixing agent. Diphenyl,di-o-tolyl, di-o-an-isyl, di-p-phenetyl, etc. may be utilized ortriphenyl- 8 0 guanidine may be employed- Further, any acid giving tothe diaryl guanidine the required solubility in-water may be used.Diphenyl guanidine hydrochloride is 'to be preferred on the basis ofcost. Also, since the hydrochloride of diphenyl guanidine can be madeinto stock solutions containing as little as 10% water, it is moreconvenient to apply than the sulfate which has a much lower solubilityin water.,'.- The acetate is very soluble in concentrated solutions, buthy- 9 drolyzes considerably 'upon being diluted to the for use intreating colored {The above process may be modified by applying'thefixing agent previous to the dye. Alcohol or other penetratingagents'may be added .to either dye or fixing solution. The free base'ofan ,aryl guanidine maybe applied from an ,alcoholic solution if desired,although organic solutions possess the-disadvantage of greater cost.

'The paper may be given a double treatment ,of the fixing bath to secureless bleeding'of the be used to apply the di lguanidme to the paper. Thedyed paper may be either wet or dry when after-treated.

The invention may be used in fixing dyestuffs upon board, wrapping,tissue, crepe, absorbent, building, cardboard, cover, news, printing orwrit- 0 ing papers. In general, the processis applicable to any surfacedyed paper requiring water-fast. colors. The paper produced by theprocess here disclosed can be moistened with drops of water and 16 thedye thereon will not spot or' run from the paper as with surface dyedpaper produced by the usual methods in which the water soluble-dye isnot rendered insoluble but is dried into the sheet.

and allowed .to remain in its original form. The D disadvantages of dyedpaper fromwhich the dye will bleed are that such paper when wet stainsthe hands or clothing or articles which maycome in contact with it andthat drops of water cause an unattractive spotting of the surface of thepaper. 2

The aryl guanidines possess the great advantage over certain otherorganicbases, such as the naphthylamines, vbenzidene and5-ethoxy-1-aminobenzothiazol which are also effective in preventing thebleeding of surface colored paper, that the aryl guanidines affect thefastness to light much less than other organic bases.

'As many, apparent and widely difl'erent embodiments of this inventionmay be made without departing from thespirit thereoffit is to beunderstood that I do not 1mm myself to the foregoing examples ordescriptions except as'lndicated in the following claims.

I claim:

prises applying a dye containing an acid group thereto and-fixing saiddye by applying to the dyed paper a substance of the group consisting ofdiand tri-aryl guanidines.- 2. The method of coloring paper which com- 5prises applying-a 'dy'e containing an acid group thereto and fixingsaiddye by applying to the dyed paper a: diaryl guanidine.

'3. The method of coloring paper which comprises applying a dyecontaining an acid group 1 1. The method of coloring paper whichcomthereto and fixing said dye by applying to the dyed paper diphenylguanidine.

4. The method of coloring paper which comprises applying a dyecontaining an acid group thereto andfixing said dye by applying tothedyed paper diphenyl guanidine in concentration exceeding aboutone-eighth mol per liter.

5. The method of coloring paper which comprises applying a dyecontaining an acid group thereto and fixing said dye by applying to thedyed paper diphenyl guanidine in concentration from about 0.5 to 25 percent.

I 6. The method of rendering dyed paper nonbleeding to water whichcomprises treating paper, dyed with a dye containing an acid group witha solution of a diaryl guanidine in excess of the theoretical amountnecessary to precipitate the dye.

Patent N0. 1,926,614.

/ cm z. BRAVES.

. centr c-Amos connection.-

a. Paper dyed with a dye containing an acid group of improvednon-bleeding quality comprising a diaryl guanidine as a fixative.

9. Paper dyed with a dye containing an acid group of improvednon-bleeding quality comp'rising diphenyl guanidine as a fixative.

10, Paper dyed with a dye containing an acid group of improvednon-bleedingrquaiity comprising diphenyl guanidine in excess of thetheoretical 7 amount necessary to precipitate the dye.

1 CARL 'Z DRAVES.

with 12. 1933.

It is herebyeertiiied' thatv error-appears in the printed specificationof the above numbered patent requiring correctionas follows: "Page 3,lines 84. -8 7, and 90, claims 8, 9, and 10,- respectively, after"group" insert the words and being; and that the said'Letters Patentshould be read with these corrections therein that the same may' conformto the record'oi the case in thcglltcnt Off ice.

sen

'Signed and sealed jth'is Zthdfly of November,

Hcpkim I Act'in gfdl omiaaioner of

